MEDLINE simiar service

Hello everybody,
I have a simple question...
Is there another reference-database service like that of MEDLINE, but for
free???
All kinds of hints are welcome..
Christian
Please mail directly.... to <heuss at urz.unibas.ch>
**************************************************************************
Christian Heuss <heuss at urz.unibas.ch>
Biocenter
University of Basel
4056 Basel
**************************************************************************